1. Field of the Invention
The present invention relates to a method of establishing an HRPD signal link, and more particularly to a method of establishing an alternate HRPD signaling link between the access terminal and the access network over a non-HRPD access and the pre-establishment of HRPD sessions over the alternate signaling link.
2. Description of the Related Art
There is interest in developing multi-mode devices, capable of seamlessly transferring data, voice and video services from one radio technology to another one, without adversely affecting the user-experience.
One such device is 3GPP2-EVDO interoperating with other wireless standards, such as 3GPP Long Term Evolution (LTE), WLAN, WiMax, etc. This type of inter-technology handoffs is gaining special attention, as there is keen interest in integrating different air-interface technologies. Also as major cellular operators migrate to 4G and newer operators in broadband space emerge, multi-mode radio devices will be needed for both intra-operator as well as inter operator roaming for the foreseeable future as 4G technologies mature.
A real-time data-session, for example, a VoIP call, that is initiated on one technology, such as LTE, may move or roam into an area where only HRPD is available. It becomes necessary to transfer the VoIP call from LTE to HRPD seamlessly and without a long delay.
However, the HRPD requires that a session is established, before it is allowed to make/receive any type of calls. The initialization and session establishment of HRPD includes the following steps, which requires signaling exchanges between a mobile device and the HRPD network: 1. Unicast Access Terminal Identifier (UATI) assignment procedure, 2. HRPD session establishment procedure, 3. Access Authentication, 4. Point-to-point protocol (PPP) set-up, and 5. IP-setup as a preparation for a future handoff to HRPD. However, the complexity and cost constraints limit the mobile device to have typically, one transmitter antenna, which is standard industry practice today.
In the example detailed above, this would require that there is an additional transmitter available for signaling exchanges for initialization and session establishment, while the device is actively transmitting and receiving on the other radio-interface.
This invention proposes a method and solution to perform the initialization and session-establishment procedure of HRPD, from a mobile active on a non-HRPD network or other air-interface, such as LTE, WLAN, WiMax, etc., so as to minimize the disruption and packet loss during handoff or transfer to HRPD network, free of having to use two transmitter antennas.
Thus, there is a need to perform the initialization and session-establishment procedure of HRPD, from a mobile active on a non-HRPD air-interface (by way of example, this term includes LTE, WLAN, WiMax and the like), so as to minimize the disruption and packet loss during handoff or transfer to the HRPD air-interface, which is cost effective, quick or user friendly and free from requiring use of two transmitter antennas, for example.